# Resistance

Discussion in 'The Projects Forum' started by DanooshDesignâ¢, Jun 23, 2010.

1. ### DanooshDesignâ¢ Thread Starter New Member

Jun 22, 2010
5
0
Hello,

is there any problem to add resistance between batteries and circuit when we want to increase the voltage?
if yes,according to the details below,how much ohms should resistance be?
also the circuit itself has resistance it self.

Circuit Details:
Required voltage ------ 4V
Required Amperage ---- (4XAA 1.5v Battery's amperage)
Voltage from battery -- 14V

Last edited: Jun 23, 2010
2. ### retched AAC Fanatic!

Dec 5, 2009
5,197
315
Resistance will drop voltage, not increase it.

I think you are saying you want 4v and you have 14v?
Or
You need to drop the voltage from the battery pack from 14vDC to 4vDC?

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3. ### Vasanthkini Member

Jun 9, 2010
40
2
Adding a resistance in the path drops the voltage and not increase it.However,the current remains the same through out.To drop 14VDC to 4VDC,employ voltage divider rule.Use the resistors in Kilo Ohm so as to reduce the noise sensitivity.

Thanks

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4. ### DanooshDesignâ¢ Thread Starter New Member

Jun 22, 2010
5
0
yes, I mean I need to drop the voltage from the battery pack from 14vDC to 4vDC (without changing batteries).
If I add a resistance,won't circuit burn? I'm afraid it'll burn.

Last edited: Jun 23, 2010
5. ### retched AAC Fanatic!

Dec 5, 2009
5,197
315
Friend, you can easily use 2 resistor to make a voltage divider.

That will drop your 14v to 7v straight away. Then you have to ask yourself if 5v will do.

You can add in a linear regulator to change the 7v to 5v easily, then use 1 diode to drop to right around 4v.

voltage divider
7805
diode

Also, you can get quick information here:

This is our eBook.

but here is a link to the voltage divider page:

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6. ### DanooshDesignâ¢ Thread Starter New Member

Jun 22, 2010
5
0
Thank you!
I'll do what you said.

Last edited: Jun 26, 2010
7. ### Vasanthkini Member

Jun 9, 2010
40
2
The circuit definitely wont smoke off because you in any case are decreasing the voltage! Make sure you add the resistance of right power rating or you might end up burning the resistor !

Thanks

8. ### DanooshDesignâ¢ Thread Starter New Member

Jun 22, 2010
5
0
I want to go to a electronic-related market to finish my project,but really thank you guys!

9. ### Tahmid Active Member

Jul 2, 2008
344
28
Hi,
You can try this circuit. With the given components, you can expect an output voltage of approximately 4.2v

Hope this helps.
Tahmid.

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10. ### DanooshDesignâ¢ Thread Starter New Member

Jun 22, 2010
5
0
wow! thank you, but you know,I want to put my circuit to a mini Remote Controlled Car on the other hand there is no any enough place to put your designed circuit into it's body.

but I've solved my problem,I just add 4 LEDs which needs 12volt in total and then I'll add 16volt battery to turn both LED circuit and main circuit,I hope this is the right way...isn't it? if it's not,tell me why. it's really important to me.

11. ### retched AAC Fanatic!

Dec 5, 2009
5,197
315
Ahh, friend, that is why it is important to tell us in the beginning what your needs are.

If you would have said what you needed the circuit to do, and where it would be used, we could have had that in mind.

Also, Tahmids circuit can be very small. You use surface mount components on your final build and double side board, VERY small.